Fully Uncoupled Electronically Controllable Sinusoidal Oscillator Employing VD-DIBAs

doi:10.4236/cs.2013.43035

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Circuits and Systems, 2013, 4, 264-268

http://dx.doi.org/10.4236/cs.2013.43035 Published Online July 2013 (http://www.scirp.org/journal/cs)

Fully Uncoupled Electronically Controllable Sinusoidal

Oscillator Employing VD-DIBAs

Data Ram Bhaskar1*, Dinesh Prasad1, Kanhaiya Lal Pushkar2

1Department of Electronics and Communication Engineering, Faculty of Engineering and Technology,

Jamia Millia Islamia, New Delhi, India

2Department of Electronics and Communication Engineering, Maharaja Agrasen Institute of Technology, Rohini,

New Delhi, India

Email: *[email protected], [email protected]c.in, [email protected]

Received March 21, 2013; revised April 22, 2013; accepted April 30, 2013

cense, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

ABSTRACT

Recently, voltage differencing-differential input buffered amplifiers (VD-DIBA)-based electronically controllable si-

nusoidal oscillator has been presented that it does not have the capability of complete independence of frequency of

oscillation (FO) and condition of oscillation (CO) as well as electronic control of both CO and FO. In this article, a new

fully-uncoupled electronically controllable sinusoidal oscillator using two VD-DIBAs, two grounded capacitors and two

resistors has been proposed which offers important advantages such as 1) totally uncoupled and electronically con-

trolled condition of oscillation (CO) and frequency of oscillation (FO); 2) low active and passive sensitivities; and 3) a

very good frequency stability factor. The effects of non-idealities of the VD-DIBAs on the proposed oscillator are also

investigated. The validity of the proposed formulation has been confirmed by SPICE simulation with TSMC 0.18 μm

process parameters.

Keywords: Sinusoidal Oscillator; Voltage-Mode; VD-DIBA

1. Introduction

Sinusoidal oscillators find various applications in signal

processing, instrumentation, measurement, communica-

tion and control systems. The class of single resistance

controlled oscillators (SRCOs) using different active

element(s)/device(s) has been of particular interest dur-

ing the last four decades because of their applications in

variable frequency oscillators. However, in these SRCOs,

electronic control of CO and FO can be obtained by re-

placing the respective controlling resistor(s) with FET

based or CMOS voltage controlled resistor(s). A careful

inspection of the available SRCOs reveals that while

many oscillators enjoy independent single element con-

trol of CO and FO, the class of fully uncoupled oscilla-

tors has not been considered adequately in the literature.

In fully uncoupled oscillator circuits CO and FO are de-

termined by two completely different sets of active and/

or passive components, that is none of the active and/or

passive components appeared in CO are involved in FO

and vice versa. This feature is very useful for realizing

voltage controlled oscillators as FO can be controlled

independently without disturbing CO, whereas the flexi-

bility of being able to control CO independently is ad-

vantageous to incorporate amplitude stabilization. In the

recent past, number of fully-uncoupled sinusoidal oscil-

lators employing different active element(s)/devices has

been introduced see [1-7] and the references cited therein.

In references [1-5] the CO and FO of the proposed oscil-

lators are adjustable through resistors (the electronic

tunability can be established by replacing one of the

grounded resistors by JFETs/MOSFETs [8,9]), whereas

in case of oscillators presented in references [6,7], both

CO and FO are electronically controllable. The VD-

DIBA was introduced by Biolek, Senani, Biolkova and

Kolka in [10] since then it has been found to be a useful

new active building block in realizing all voltage-mode

pass filters [11], inductance simulation [12], universal

biquad filter [13] and an electronically controllable sinu-

soidal oscillator [14]. Although the paper presented by

the authors in [14] employs two VD-DIBAs, two grounded

capacitors and one grounded resistor but this circuit does

not have the capability of complete independence of CO

and FO as well as electronic control (only FO is elec-

tronically controllable). Therefore, the purpose of this

*Corresponding author.

D. R. BHASKAR ET AL. 265

paper is, to propose a new fully uncoupled electronically

controllable sinusoidal oscillator employing two VD-

DIBAs, two grounded capacitors and two resistors, which

offers 1) fully uncoupled and electronically controlled

CO and FO, 2) low active and passive sensitivities, and 3)

a very good frequency stability factor. The feasibility of

the proposed oscillator has been demonstrated by SPICE

simulation with TSMC 0.18 μm process parameters.

VD-DIBA(+) VD-DIBA(-)

V_V

ZV V

C1R1

2. The Proposed Fully Uncoupled Oscillator

The schematic symbol and behavioral model of the VD-

DIBA are shown in Figures 1(a) and (b) respectively

[11]. The VD-DIBAs can be described by the following

set of equations:

000

110

























 



(1)

Figure 2. The proposed fully-uncoupled electronically con-

The proposed new fully-uncoupled electronically con-

trollable sinusoidal oscillator circuit is shown in Figure

Assuming that the VD-DIBAs are characterized by

Equation (1), the characteristic equation (CE) of Figure

2 can be given by:

212

RCC



ss g







 (2)

From this CE, the CO and FO can be found as:









(3)

V+

VD-DIB

(a)

V+

V-

VzVv

Vz-Vv

(b)

Figure 1. (a) Schematic symbol; (b) Behavioral model of

trollable sinusoidal oscillator.

212

RCC



 (4)

Therefore, from Equations (3) and (4) it is clear that

FO and CO are fully decoupled and electronically con-

trollable i.e. FO is independently controllable by trans-

conductance 2

of the VD-DIBA(−), whereas CO is

also electroni controllable through the transconduc-

tance 1

cally

of VD-DIBA(+).

3. Non-Ideal Analysis

f VD-DIBA i.e. RZ and CZ, Considering the parasitics o

the parasitic resistance and the parasitic capacitance of

the Z-terminal respectively. Taking the non-idealities

into account, namely the voltage of W-terminal













VV where





 

pp and















nn e voltage trackingrs of

Z-terminal and

denote th erro

V-terminal of the VD-DIBA (+/−) re-

spectively, then the expression for CE becomes:





VD-DIBA.



112

sC g C

RR R

CRR

RR R

22sC CC



















































(5)

From Equation (5), the CO and FO can be given by:



CO:





1212 0

























 

CgC

(6)

D. R. BHASKAR ET AL.

266

FO:



mmz

RRR R

CCC















 (7)

ivities of 0

The sensit



with respect to active and pas-

sive elements are calculated as:



2mz

R R













221

112

mmz

RRR R

Sgg

RRRR

























 



































 





















000

221

112

1,1

mmz

CCC

RR g

RRRR

RR g

RRR R

SSS





















 





















 

















 

(8)

An inspection of Equation (8) reveals that the a

and passive sensitivities of 0

ctive



are found to be low.

4. Frequency Stability

Frequency stability is an important figure of merit for

an F

y sinusoidal oscillator. Using the definition of the fr-

equency stability factor Sas given in [5,8]



F S



1









u (where



u is the normalized fre-

quency and





u denotes the phase of the open-loop

transfer function), with 1

, 

CCCg



2

ng , the SF of this oscillator is found to

be 2n. Thus the new proposed oscillator circuit offers

very high frequency stability f

oscillator circuit has been simu

lated using the CMOS-based VD-DIBA [14]. The vari-

omponent

7 K

IB7 = 30 μA. The transcon-

ere controlled through the

and

actor for larger values of n.

5. Simulation Results

The proposed sinusoidal-

ous cvalues used were C1 = C2 = 0.05 nF, R1 =

1.6 Ω and R2 = 10 K, the CMOS VD-DIBA was bi-

ased with ±1 V D.C. power supplies with IB1 = IB2 = IB3 =

IB4 = IB5 = IB6 = 150 μA and

ductances of VD-DIBAs w

respective bias currents. The SPICE generated output

waveforms indicating transient and steady state re-

sponses are shown in Figures 3(a) and (b) respectively.

From SPICE simulations {Figures 3(a) and (b)}, the

oscillations are observed to be quite stable and the fre-

quency of generated sine wave was found as 731.88 KHz.

The THD of the output waveform was found as 1.159%.

Figure 4 shows the Monte-Carlo simulations which pro-

vide the robustness of the oscillator circuit of Figure 2

by taking sample result for ±10% variations in R1. Simu-

lation results, thus, confirm the workability of the pro-

012

x 10

-4

-0.1

-0.08

-0.06

-0.04

-0.02

0.02

0.04

0.06

0.08

0.1

Voltage (V)

Time (S)

(a)

0.1

0.08

0.06

0.04

0.02

-0.02

-0.04

-0.06

-0.08

1.5

-0.1 1.51 1.521.53 1.54 1.551.56 1.57 1.58 1.591.6

x 10

-4

Time (S)

Voltage (V)

(b)

Figure 3. (a) Transient output waveform; (b) Steady state

response of the output.

D. R. BHASKAR ET AL.

267

Time

0s20us40us60us80us100us 120us 140us 160us 180us200us

V(3)

-200mV

200mV

1/ Period(V(3))

720K 724K 728K 732K 736K 740K744K

SEL>>

n samples= 9

n divisions= 10mean= 731819

sigma= 4431.69minimum= 723940

10th %ile= 723940median= 731884

90th %ile= 737724maximum

3*sigma = 737724

= 13295.1

Figure 4. Result of Monte-Carlo simulation of oscillator circuit of Figure 2.

Table 1. Comparison with other previously known fully uncoupled sinusoidal osc illators.

Reference Number No. of Active Elements No. of Passive

Elements

No. of Grounded

Capacitors

Independent Electronic

Tunability in Both CO and FO

[1] 2 6 2 NO

[2] 3 4 - 6 2 - 3 NO

[3] 3 5 2 NO

[4] 1 - 3 3 - 7 2 - 3 NO

[5] 3 6 2 NO

[6] 4 YES

[7] 2 YES

[14] NO

2 2

2 3 2

Proposed 2 4 2 YES

posed oscillator. A comparison with other previously

known fully uncoupled sinusoidal oscillators has been

given in Table 1.

6. Concluding Remarks

A new siidal oscillator with fully decoupled and

electronically controllable both frequency of oscillation

and condition of oscillation has been presented. The new

oscillator configuration also enjoy1) low active and

passive sensitivities and 2) a very good frequency stabil-

ity factr values of n. Tobustness of the

roposed oscillator circuit has been confirmed by the

Quadrature Sinusoidal Oscillator,” Journal of RF-Engi-

neering and Telecommunication (GermanyVol. 61, No.

3-4, 2007, pp.2-104.

M. T. Abuelmatti, “New Sinusoidal Oscis with Fully

Uncoupled Con Frequency and Condi-

tion Using Thre CCII + s,” Analog Integrated Circuits

and Signal Processing, Vol. 24, No. 3, 2000, pp. 253-261.

doi:10.1023/A

[2] llator

ntrol of Oscillatio

:1008321911123

nuso

or for largehe r

[3] D. R. Bhaskar R. Senani . K. Singh,

“New CFOA-Based Sinusoidal Oscillatotaining In-

dependent Cool of Oscillation FrequEven under

the Influence arasitic Impedances,” Analog Integrated

Circuits and Snal Processing, Vol. 73, 2012, pp. 427-

437. doi:10.10 /s10470-012-9896-6

, S. S. Gupta,and A

rs Re

ntr ency

of P

[4] A. M. Soliman, “Current Feedback Operational Amplifier

Monte-Carlo analysis. The workability of the proposed

configuration has been established by SPICE simulations

with TSMC 0.18 μm process parameters.

Based Oscillators,” Analog Integrated Circuits and Signal

Processing, Vol. 23, No. 3, 2000, pp. 45-55.

doi:10.1023/A:1008391606459

[5] D. R. Bhaskar, “Realization of Second Order Sinusoidal

Oscillator/Filters with Non-Interacting Controls Using

CFAs,” Journal of RF-Engineering and Telecommunica-

tion (Germany), Vol. 57, No. 1-2, 2003, pp. 12-14.

[6] D. R. Bhaskar and R. Senani, “New Linearly Tunable

REFERENCES

[1] W. Tangsrirat and S. Pisitchalermpong, “CDBA-Based

D. R. BHASKAR ET AL.

268

CMOS-Compatible OTA-C Oscillators with Non-Inter-

acting Controls,” Microelectronics Journ

2, 1994, pp. 115-123.

al, Vol. 25, No.

90108-2doi:10.1016/0026-2692(94)

[7] D. Prasad, M.haskar, “Electroni-

cally Controll Explicit Current-

Srivastava and D. R. B

able Fully—Uncoupled

Mode Quadrature Oscillator Using VDTAs and Grounded

Capacitors,” Circuits and Systems, Vol. 4, No. 2, 2013,

pp. 169-172. doi:10.4236/cs.2013.42023

[8] D. R. Bhaskar and R. Senani, “New CFOA-Based Single-

Element-Controlled Sinusoidal Oscillators,” IEEE Trans-

actions on Instrumentation and Measurement (USA), Vol.

55, No. 6, 2006, pp. 2014-2021.

doi:10.1109/TIM.2006.884139

[9] S. S. Gupta and R. Senani, “Realisation of Current-Mode

SRCOs Using All Grounded Passive Elements,” Fre-

quenz, Vol. 57, No. 1-2, 2003, pp. 25-36.

doi:10.1515/FREQ.2003.57.1-2.25

[10] D. Biolek, R. Senani, V. Biolkova and Z. Kolka, “Active

Elements for Analog Signal Processing; Classification,

Review and New Proposals,” Radioengineering, Vol. 17

r Voltage-Mode

5-2

No. 4, 2008, pp. 15-32.

[11] D. Biolek and V. Biolkova, “First-Orde

All-Pass Filter Employing One Active Element and One

Grounded Capacitor,” Analog Integrated Circuits and

Signal Processing (USA), Vol. 65, No. 1, 2009, pp. 123-

129. doi:10.1007/s10470-009-943

. L. Pushkar, “Realization

ers,” Active

ts, 2011, Article ID

l Input Buffered Amplifier,” Cir-

[12] D. Prasad, D. R. Bhaskar and K

of New Electronically Controllable Grounded and Float-

ing Simulated Inductance Circuits Using Voltage Differ-

encing Differential Input Buffered Amplifi

and Passive Electronic Componen

101432.

[13] K. L. Pushkar, D. R. Bhaskar and D. Prasad, “Voltage-

Mode Universal Biquad Filter Employing Single Voltage

Differencing Differentia

cuits and Systems, Vol. 4, No. 1, 2013, pp. 44-48.

doi:10.4236/cs.2013.41008

[14] D. Prasad, D. R. Bhaskar and K. L. Pushkar, “Electroni-

cally Controllable Sinusoidal Oscillator Employing CMOS

VD-DIBAs,” ISRN Electronics, 2013, Article ID 823630.